The Third Generation Partnership Project (3GPP) unites six telecommunications standards bodies, known as “Organizational Partners,” and provides their members with a stable environment to produce the highly successful Reports and Specifications that define 3GPP technologies. A mobile device, also called a User Equipment (UE), may operate in a wireless communication network that provides high-speed data and/or voice communications. The wireless communication networks may implement circuit-switched (CS) and/or packet-switched (PS) communication protocols to provide various services. For example, the UE may operate in accordance with one or more of an Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-FDMA) networks, etc. The terms “networks” and “systems” are used herein interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband-CDMA (W-CDMA) and Low Chip Rate (LCR) cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDM®, etc. UTRA, E-UTRA, and GSM are part of Universal Mobile Telecommunication System (UMTS). Long-Term Evolution (LTE) is a new release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in specification documents from 3GPP. These various radio technologies and standards are known in the art.
Long Term Evolution or LTE is a next generation standard for wireless communication of high-speed data for mobile phones and data terminals. It is based on the GSM/EDGE and UMTS/HSPA (Universal Mobile Telecommunication System/High Speed Packet Access) network technologies, increasing the capacity and speed using new modulation techniques. The IP-based LTE network architecture, called the Evolved Packet Core (EPC) supports seamless handovers for both voice and data to cell towers with older network technology such as GSM, UMTS and CDMA2000. The LTE technology is adapted for a smooth evolution from earlier 3GPP systems. VoLTE or Voice Over LTE is a standardized scheme developed to transmit voice traffic over the IP-based LTE network.
The Evolved Packet Core (EPC) is the latest evolution of the 3GPP core network architecture first introduced in Release 8 of the standard. In EPC, the user data and the signaling data are separated into the user plane and the control plane. The EPC is composed of four basic network elements: the Serving Gateway (SGW), the Packet Data Network Gateway (PDN GW or PGW), the Mobility Management Entity (MME), and the Home Subscriber Server (HSS). The EPC is connected to external networks, which can include the IP Multimedia Core Network Subsystem (IMS).
The Home Location Register (HLR) in the CS core network and the Home Subscriber Server (HSS) in the IMS are typically the network nodes that contain master copies of the subscriber profile databases. The data stored in the databases include data such as Mobile Subscriber Integrated Service Digital Network (MSISDN) number, International Mobile Subscriber Identity (IMSI) number, Subscriber Identity Module (SIM) card details, service selections, and General Packet Radio Service Tunneling (GPRS) as well as Universal Mobile Telecommunications System (UMTS) settings. The database is also used to store a master copy of supplementary services parameters for each subscriber. Supplementary services settings stored in the database may include multi-party service (MPTY), explicit call transfer (ECT), call deflection (CD), call forwarding (CF), call hold (CH), and call barring.